This invention relates to a communication control method and an equipment for implementing the same, and more particularly to a communication control method inclusively having test function for testing (checking) the operation of the equipment (provided for communication control) at the physical layer in the ATM communication, and an equipment for implementing such a method.
In recent years, as a system in which high speed and large capacity data communication can be made, development in regard to the ATM communication is being carried out.
In the ATM communication, a series of data processing within the communication equipment are carried out in the state caused to be of hierarchical (layered) structure consisting of plural protocol (control procedure) layers. In this protocol hierarchical structure, the layer located at the lowest level is the physical layer.
In carrying out such ATM communication, conversion is carried out between the data form at the physical layer, i.e., the data form on the transmission line and the data form at the layer higher than the physical layer. The data form on the transmission line is the form of the frame in conformity with, e.g., SONET/SDH standard, etc. The layer which is higher than the physical layer by one is the ATM layer. The data form in this layer is ATM cell. The ATM cell is data packet having unit length of 53 bytes, and consists of header of 5 bytes in which destination of transmission, etc. is described and payload of 48 bytes in which user data is stored.
The outline of the configuration of a communication control equipment 300 in the physical layer related to this invention is shown in FIG. 1. The communication control equipment 300 includes a receiving system assembled of circuits 305xcx9c308, a transmitting system assembled of circuits 301xcx9c304, a loop back circuit comprised of a selector 309 provided therebetween, and a host interface 310 for carrying out interface with the host CPU.
In the transmission system, when ATM cell is sent from an ATM layer control unit 400, it is inputted to the transmission cell processing section 302 through the transmission cell interface 301. In the transmission cell processing section 302, after necessary processing is implemented to the header of the ATM cell, the ATM cell thus processed is transferred to the transmission frame assembling section 303. In this case, for a time period during which no data cell is sent to the control equipment 300 of the physical layer (hereinafter referred to as physical layer control unit as occasion may demand) from the ATM layer control unit 400, idle cell indicating that no data cell is sent is generated at the transmission cell processing section 302, and the idle cell thus generated is transferred to the transmission frame assembling section 303 in place of the data cell.
At the transmission frame assembling section 303, data cell or idle cell is converted from the data form of the ATM cell into the data form on the transmission line so that frame data is provided. Thereafter, this frame data is transferred from the transmission line interface 304 to the transmission line.
In the receiving system, frame data represented in the data form on the transmission line is inputted to the receiving frame disassembling section 306 through the receiving line interface 305 and via selector 309 of which detail will be described later. At the receiving frame disassembling section 306, the frame data is disassembled into the portion where cells are stored thereof and the portion of frame management data except for the above. The portion of the frame management data is stored into memory, etc. provided within the receiving frame disassembling section 306. On the other hand, the portion where cells are stored is transferred to the receiving cell processing section 307. At the receiving cell processing section 307, cell synchronization is implemented with respect to the portion where cells are stored so that boundaries between cells are caused to become clear. Thereafter, various processing corresponding to the header pattern are implemented thereto. The result of this processing is indicated at the status register provided within the host interface 310. The cells extracted from the frame data in a manner as described above are outputted to the ATM layer control unit 400 through the receiving cell interface 308.
Meanwhile, data cell or idle dell outputted from the transmission frame assembling section 303 is ordinarily transmitted to the transmission line interface 304. However, in the case where test or check of the internal operation of the control unit 300 is carried out, output of the selector 309 is switched, thereby making it possible to allow the cell to undergo loop back to the receiving frame disassembling section 306. As stated above, the selector 309 is provided for the purpose of test. Ordinarily, output of the receiving line interface 305 is delivered to the receiving frame disassembling section 306.
At the time of test, output of the transmission frame assembling section 303 is delivered to the receiving frame disassembling section 306, whereby data is sent from the transmission system to the receiving system. At the time of carrying out test, output of the selector 309 is initially switched to make such a setting that output of the transmission frame assembling section 303 is delivered to the receiving frame disassembling section 306. Thus, test cell in the form of the ATM cell inputted from the ATM layer control unit 400 to the physical layer control unit 300 is converted into the form of the frame data at the transmission frame assembling section 303. The frame data thus obtained is inputted to the receiving frame disassembling section 306 through the selector 309. At the receiving frame disassembling section 306, the frame data including the test cell therein is disassembled into the portion where cell is stored and the frame management data portion except for the above. Then, processing corresponding to the header pattern is carried out by the receiving cell processing section 307. The processing result obtained at this time is monitored by the host computer through the host interface 310. Thus, the host computer can survey or confirm whether or not the internal processing is normally carried out at the receiving cell processing section 307. In this case, by rewriting, in dependency upon the test purpose, the header pattern of the test cell that the ATM layer control unit 400 delivers to the physical layer control unit 300, tests can be made with respect to various functions. This rewrite operation of the header pattern is carried out by the host computer.
A Alternatively, there were instances where dedicated evaluation equipment is provided at the external in place of the ATM layer control unit 400 to generate test cells by using this equipment to carry out test.
Further, in the physical layer control unit 300, it is also conceivable to input, without using the selector 309, test cell in the form of frame data from the transmission line to the receiving line interface 305 to deliver it to the receiving frame disassembling section 306 and the receiving cell processing section 307. However, also in this case, dedicated evaluation equipment is required. Eventually, the communication control equipment (unit) shown in FIG. 1 requires dedicated evaluation equipment in all of the above-described cases. The reason thereof will be described in detail.
As an item of test carried out by inputting test cell to the physical layer control unit 300 in place of the communication data, there are tests of GFC (General Flow Control) function, bit error correction function of header, and cell counter function, etc. The GFC function is a function for carrying out operation to stop sending-out of transmit data in accordance with the content of the leading 4 bits of the header of the received cell, etc. The bit error correction function of header, is a function to detect and correct error in the case where error takes place in any 1 bit of the header portion of 40 bits. The cell counter function is a function to count the number of valid cells except for invalid cells like idle cell among received plural cells.
In order to test or check such functions, it is necessary to rewrite the header of the test cell in accordance with the test purpose. However, in the communication control equipment shown in FIG. 1, the function to generate test cells corresponding to the purpose of tests to send out them to the portion to be tested was not provided. For this reason, test could not be carried out if the evaluation equipment, etc. is installed at the external of the physical layer control unit.
In order to provide such dedicated evaluation equipment, at the stage for developing the physical layer control unit, development including the evaluation equipment as well is required. Moreover, the evaluation equipment itself is expensive, leading to increased development cost.
In addition, after the test is completed and the communication system in which the physical layer control unit is assembled is transferred to user, it is extremely difficult that user carries out test or check of the physical layer control unit if no dedicated evaluation equipment is provided. It is readily considered that if the communication system is continuously used for a long time period, there result circumstances where any fault takes place in the physical layer control unit, leading to obstacle to communication. However, it was difficult that user carries out maintenance and check of the product.
As stated above, in the case of testing or checking the physical layer control equipment (unit) shown in FIG. 1, it is necessary to provide the dedicated evaluation equipment at the external, leading to increase in the development term and the cost. In addition, it was difficult that user who uses such equipment carries out maintenance and check.
This invention has been made in view of the above-described circumstances, and its object is to provide a communication control method and equipment therefor which can carry out test by the physical layer control unit itself without providing evaluation equipment dedicated for test at the external of the equipment, and which can reduce the test cost and easily carry out maintenance and check.
A communication control equipment of this invention is directed to an equipment including a transmission system adapted so that data cell sent from an ATM layer control unit is inputted thereto to convert the data cell into frame data to transmit it to transmission line, a receiving system adapted so that frame data sent from the transmission line is inputted thereto to convert the frame data into data cell to transmit it to the ATM layer control unit, and a loop-back line or circuit for carrying out loop-back of data cell inputted to the transmission system to deliver it to the receiving system, wherein the transmission system comprises a transmission cell processing section including: an idle cell generating circuit for generating idle cell to output it; a test cell generating circuit for generating test cell to output it; and selector means operative so that when data cell sent from the ATM layer control unit is delivered thereto, it outputs this data cell, when output of test cell is designated from the external in the case where no data cell exists, it outputs the test cell that the test cell generating circuit outputs, and when no data cell exists and output of the test cell is not designated from the external, it outputs the idle cell that the idle cell generating circuit outputs.
In accordance with this invention, since, within the communication control unit corresponding to the physical layer, it is possible to generate test cell to carry out internal test of the communication control unit, dedicated evaluation equipment for test is unnecessary, thus making it possible to reduce the test time and the cost.
In this case, there may be employed a configuration in which the transmission system includes a transmission cell interface adapted so that data cell sent from the ATM layer control unit is inputted thereto and outputted synchronized with an internal clock of the transmission system, a transmission cell processing section adapted so that the data cell outputted from the transmission cell interface is delivered thereto to implement a predetermined processing thereto to output data thus processed, whereby for a time period during which the data cell is not outputted from the transmission cell interface, the transmission cell processing section generates idle cell to output it, a transmission frame assembling section adapted so that the data cell or the idle cell outputted from the transmission cell processing section is delivered thereto to convert it into frame data to output the frame data thus obtained, and a transmission line interface adapted so that the frame data outputted from the transmission frame assembling section is delivered thereto and transferred to the transmission line,
the receiving system includes a receiving line interface adapted so that frame data sent from the transmission line is inputted and outputted, a selector supplied with the frame data outputted from the receiving line interface and the frame data outputted from the transmission frame assembling section, whereby at the time of the ordinary (normal) operation, the selector outputs the frame data outputted from the receiving line interface, and at the time of test, the selector outputs the frame data outputted from the transmission frame assembling section, a receiving frame disassembling section supplied with the frame data outputted from the selector to disassemble it into cell storage portion and frame management data storage portion to output the cell storage portion, a receiving cell processing section supplied with the cell storage portion outputted from the receiving frame disassembling section to implement a predetermined processing thereto to output the cell storage portion thus processed as data cell, and a receiving cell interface supplied with the data cell outputted from the receiving cell processing section, and
the idle cell generating circuit, the test cell generating circuit and the selector means is included in the transmission cell processing section.
Alternatively, communication control equipment of this invention comprises, in the transmission system, a transmission cell interface operative so that when data cell is inputted thereto, it generates a valid cell flag signal indicating that valid data cell exists to output the valid cell flag signal along with the data cell, and to generate a cell byte count signal for counting the number of bytes of cell to be outputted to output it, and a transmission cell processing section operative to generate idle cell and test cell to select any one of the data cell, the idle cell and the test cell on the basis of the valid cell flag signal and a test cell sending start signal inputted from the external to output selected one in accordance with the cell byte count signal, wherein the transmission cell processing section includes an idle cell generating circuit for generating idle cell to output it in accordance with the cell byte count signal, a test cell generating circuit supplied with data related to test purpose from the external to generate test cell including this data to output it in accordance with the cell byte count signal, a selector control circuit operative to generate a select signal to select the data cell when the valid cell flag signal is delivered thereto, to select the test cell when the valid cell flag signal is not delivered thereto and the test cell sending start signal is delivered thereto, and to select the idle cell when both the valid cell flag signal and the test cell sending start signal are not delivered thereto to output the select signal, and a selector for selecting any one of the data cell, the idle cell and the test cell on the basis of the select signal to output selected one.
The selector control circuit comprises a sending number of test cells setting register in which the number of test cells to be sent out is set in advance, a sending number of test cells counter for counting the number of the test cells which have been sent out, a comparison circuit for comparing the number set at the sending number of test cells setting register and the number that the sending number of test cells counter has counted to output a reset signal when the number of the test cells which have been sent out reaches the set number, a test cell flag generating circuit operative so that when the test cell sending start signal is delivered thereto, it generates, in accordance with the cell byte count signal, a test cell flag signal for determining timing at which the test cell is sent out to output it, and when the reset signal is delivered thereto, it stops output of the test cell flag signal, and a select signal generating circuit operative to generate a select signal to select the data cell when the valid cell flag signal is delivered thereto, to select the test cell when the valid cell flag signal is not delivered thereto and the test cell flag signal is delivered thereto, and to select the idle cell when both the valid cell flag signal and the test cell flag signal are not delivered thereto, thus to output the select signal to the selector.
Alternatively, the selector control circuit may further comprise a register operative so that when the test cell sending start signal is inputted thereto from the external, it holds the test cell sending start signal to output it, and the test cell flag generating circuit may be such that when the test cell sending start signal is outputted from the register, it generates a test cell flag signal for determining timing at which the test cell is sent out in accordance with the cell byte count signal to output it, and when the reset signal is delivered thereto, it stops output of the test cell flag signal.
A communication control method of this invention is directed to a method in which data cell sent from an ATM layer control unit is inputted to a transmission system to convert it into frame data to transmit the frame data to transmission line, and frame data sent from the transmission line is inputted to a receiving system to convert it into data cell to transmit the data cell to the ATM layer control unit, thus to allow data cell inputted to the transmission system to undergo loop back to deliver it to the receiving system, wherein, in the transmission system, the method comprises generating idle cell to output it, and generating test cell to output it, whereby when data cell sent from the ATM layer control unit is delivered thereto, this data cell is outputted, when output of the test cell is designated from the external in the case where no data cell exists, the test cell that the test cell generating circuit outputs is outputted, and when no data cell exists and output of the test cell is not designated from the external, the idle cell that the idle cell generating circuit outputs is outputted.
Alternatively, a communication control method of this invention is such that, in the transmission system, the method comprises a first step of generating, when data cell is inputted thereto, a valid cell flag signal indicating that valid data cell exists to output it along with the data cell, and generating a cell byte count signal for counting the number of bytes of cell to be outputted, and a second step of generating idle cell and test cell to select any one of the data cell, the idle cell and the test cell on the basis of the valid cell flag signal and a test cell sending start signal delivered from the external to output selected one in accordance with the cell byte count signal, wherein the second step includes a step of generating idle cell to output it in accordance with the cell byte count signal, a step of being supplied with data related to test purpose from the external to generate test cell including this data to output it in accordance with the cell byte count signal, a step of generating a select signal to select the data cell when the valid cell flag signal is given, to select the test cell when the valid cell flag signal is not given and the test cell sending start signal is given, and to select the idle cell when both the valid cell flag signal and the test cell sending start signal are not given to output the select signal, and a step of selecting any one of the data cell, the idle cell and the test cell on the basis of the select signal to output selected one.
The step of generating the select signal to output it includes a step such that the number of test cells to be sent out is set in advance, a step of counting the number of test cells which have been sent out, a step of comparing the number set at the sending number of test cells setting register and the number that the sending number of test cells counter has counted to output a reset signal when the number of the test cells which have been sent out reaches the set number, a step of generating, in accordance with the cell byte count signal, a test cell flag signal for determining timing at which the test cell is sent out to output it, and stopping output of the test cell flag signal when the reset signal is given, and a step of generating a select signal to select the data cell when the valid cell flag signal is given, to select the test cell when the valid cell flag signal is not given and the test cell flag signal is given, and to select the idle cell when both the valid cell flag signal and the test cell flag signal are not given, thus to output the select signal.